-----------------------------------------
--- Big-step SOS: Adding print to IMP ---
-----------------------------------------

Suggested steps to follow in order to extend the oringinal big-step SOS
of IMP in Maude to include a print statement:

1) Modify imp-bigstep.maude: Include output.maude at the begining, and 
   add Maude commands for executing sumPrintPgm at the end.

2) Run imp-bigstep.maude: Everything working before should still work;
   sumPrintPgm should stay unchanged (big-step SOS either reduces a program
   all the way through, or it does not reduce it at all).

3) Modify imp-semantics-bigstep.maude:
   a) Include module OUTPUT in module IMP-CONFIGURATIONS-BIGSTEP.
   b) Add a new output component to the result configurations holding only a state.
   c) Modify the existing big-step SOS rules using the old result state
      configurations (i.e., the rules of all statements) to work with
	  the new result configurations holding both a state and an output.
   d) Change the rule for variable declarations to also report the output
      generated by evaluating the top-level statement.
	  
4) Run imp-bigstep.maude: Everything working before should still work, and
   should include and empty output buffer in the result configurations;
   sumPrintPgm still stays unchanged.

6) Add the actual big-step SOS of print, which consists of one rule.

7) Run imp-bigstep.maude and check that all programs evaluate properly.


------------------------------
--- Observations, thoughts ---
------------------------------

1) Result state configuration had to change in order to also hold the output.

2) Consequently, all rules corresponding to statements had to change, too.

3) We also had to change the rule for programs, to propagate the output.
